Airports in northern climates are obliged to employ deicing procedures on aircraft when either hoarfrost or freezing precipitation is encountered. The use of deicing fluid (traditionally propylene glycol or ethylene glycol) results in residue on the ground which, if allowed to enter a stormsewer system, would contaminate the natural environment. Other environmentally unacceptable liquids encountered at airports are fuels, hydraulic fluids, lavatory truck spills, oils and snow melting chemicals such as urea. The discharge of such substances into receiving streams and lakes has been ruled environmentally unacceptable. Accordingly, such substances should be prevented from entering the storm sewer systems which can happen most commonly at storm water catch basins. Such catch basins located at airports, or vehicle service stations, should be equipped with implements, or structures, for intercepting harmful contaminants with subsequent removal or discharge into holding or treatment facilities, while permitting uncontaminated rain water to drain into the sewer system.
U.S. Pat. No. 4,136,010 to Pilie et al. describes an exemplary catchbasin structure having a peripheral trough connected through a valve to a receiver system. The structure enables a selective interception and recovery of contaminants entering the catchbasin. The structure fulfils its function satisfactorily except during heavy rainfalls where the runoff, sometimes carrying pollutants such as deicing fluid, cannot be accommodated by the capacity of the trough and the associated conduits, the result being an overflow of contaminated water into the storm sewer system.
Canadian Patent No. 38,412 issued in 1892 describes a concrete gully for installation in a catchbasin, the gully having a hinged trap for allowing the flow of liquids into the catchbasin but preventing or reducing the emission of sewer gas therefrom.
Various catchbasin constructions are also described in U.S. Pat. No. 5,032,264 to Geiger, U.S. Pat. No. 2,993,600 to Ressler and in Canadian Patent No. 307,563 to Egan.